270 



DISCOVERY 



hundred miles before they melt or come to rest on 

 the shore of Newfoundland or e\'en farther south, 

 breaking up like ships aground. 



The fossil- bearing rocks it was our aim to investigate 

 during the summer of 1921 are exposed along the 

 shore and in the ravines of Disko and other islands, 

 and especially on the Nugssuaq peninsula. Most of 



A VII'.W XHAR CODIlAi . 

 Showiag part oi the high basaltic plateau of horizontal beds of lava and ash 

 and. below the suow-covered talus slopes, the darker hummocks of ,\rchjeaa 

 gneiss ; grasses on the sandy beach in the foreground. 



them were deposited during the Cretaceous period ; 

 others are Tertiary in age.^ Slabs of rock detached 

 with the aid of a pickaxe from the side of a ravine 

 where the hills are made of a succession of sheets of 

 sediment — the sands and muds of some ancient lake 

 or lagoon — are found to be covered with the clearly 

 outlined impressions of large leaves like those of the 

 Plane or Tulip tree, fronds of ferns hardly distinguish- 

 able from species (of the genus Gleichenia) living to-day 

 in tropical and sub-tropical countries, twigs and cones 

 of Conifers, some of which are almost identical with 

 those of the Mammoth tree (Sequoia gigantea) now 

 confined to a narrow strip of the Californian coasts, 

 and massive stems of forest trees. None of the leaves 

 preserved in the Greenland rocks have a greater 

 fascination for the student of the past history of 

 living plants than those of the genus Ginkgo. This 

 genus is now represented by a single species, the 

 Maidenhair tree (Ginkgo hiloba), which is sometimes 

 said to occur in a wild state in China, though it is 

 probable that even in China and Japan, where it 

 grows abundantly, it exists only as a cultivated tree 

 associated in the Oriental mind with some religious 

 symbolism. Some of these fossil leaves are indis- 

 tinguishable from those of the sole survivor of this 

 ancient genus at several localities within the Arctic 

 Circle as in many other regions of both the Old 

 and New World ; and their preservation strikinglv 



' The Cretaceous period is the first period in the Mesozoic 

 or Secondary era. This era is the third oldest in geological 

 time, being directly preceded by the Tertiary. See Discovery, 

 vol. iii, No. 29, p. 115. 



illustrates the possibilities, offered bv a studv of the 

 records of the rocks, of connecting the present with 

 the past, of following the wanderings over the world 

 and of tracing the rise and fall in their fortunes, of 

 still living members of the plant kingdom. - 



These fragmentary relics, " the ghostlv language of 

 the ancient earth," suggest problems that are more 

 easily stated than solved. Two among the problems 

 which exercise the ingenuity of geologists and botanists 

 may be mentioned: if, as seems certain, the climate 

 of Greenland was warm enough to support a vegeta- 

 tion, including forest trees and other plants closely 

 related to species now growing in warm temperate 

 and sub-tropical districts in North America, southern 

 Europe, China, and elsewhere, what were the causes 

 for the change to the present conditions ? Of the 

 plants that exist in Greenland some occur also in 

 different parts of Europe, others have their nearest 

 relatives in North America. Where was the original 

 home of the Arctic floras, and what was their fate 

 during and subsequent to the Glacial period which 

 reduced North America and North and Central Europe 

 to much the same condition as that of Greenland to- 

 day ? Much has been written on the causes governing 

 climatic changes in the past ; but the question is still 

 under discussion. Mr. Porsild, the Director of the 

 Danish Arctic Station, has recently summarised the 

 views of botanists on the origin of Arctic floras and 

 on the effect of the Glacial period on the pre- glacial 

 vegetation : he believes that the Ice Age was fatal 

 to the vegetation and that the present plant popula- 

 tion of the country arrived across Smith Sound on the 

 north-west and spread over the ice-free fringe of 

 Greenland.^ 



Thomas Hardv in The Return of the Native speaks of 

 Ch'm Yeobright walking alone on the heath " when 

 the past seized upon him with its shadowy hand, and 

 held him there to listen to its tale. His imagination 

 would then people the spot with its ancient inhabi- 

 tants." Similarly the waifs and strays from the 

 vegetation of the past enable us with a certain degree 

 of accuracy to reclothe the hills with plants of other 

 days and other climes. It is impossible with precision 

 to interpret in degrees of temperature what the buried 

 leaves and twigs indicate ; but we may safely say 

 that they belong to plants which could not have 

 e.xisted under conditions comparable to those endured 

 by the present Arctic vegetation. 



Many of the localities visited were on uninhabited 

 coasts where the land rose gradually inland for a few 



- For a fuller account of Ginkgo and other survivals, see 

 Links with the Past in the Plant World, by A. C. Seward. (A 

 volume of the Cambridge Manuals of Science and Literature.) 



^ Mr. Porsild's article is in a comprehensive work on Green- 

 land recently published in Copenhagen. (Greiilaiid, 1 vols. 

 Edited by G. C. Amdrup and others. Copenhagen, 192 1.) 



